Arrangement for driving rotary compressors



March 13, 1934. F. SA SS 1,951,211

ARRANGEMENT FOR DRIVING ROTARY COMPRESSORS Filed June 22, 1932 Inventor; Friedrich Sass, by His Ab'borheg.

Patented Mar. 13, 1934 UNITED STATES PATENT ARRANGEMENT FOR DRIVING ROTARY COMPRESSORS Friedrich Sass, Berlin-Charlottenburg, Germany, assignor to. General Electric Company, a corporation of New York 2 Claims.

The present invention relates to an arrangement for driving rotary compressors from reversible engines such as internal combustion engines where the compressors serve for supplying scavenging air to the cylinders of the engi-nes. It has already been suggested to drive a rotary compressor directly from the reversible engine. As the efiiciency of an ordinary compressor is considerably affected when driven in 1 4 reversed direction, it was heretofore necessary to provide special compressor constructions with adjustable blades or impellers and means for changing the adjustment with changing direction of rotation. It was also necessary to provide in view of the changing direction of rotation adjustable suction and outlet conduits for imparting the proper direction to the stream of fluid at the different directions of rotation. It i can be readily seen that these arrangements are rather complicated and expensive.

The object of the present invention is to provide an improved arrangement for driving compressors from reversible engines whereby the compressor is at all times rotated in the same direction irrespective of the direction of rotation of the reversible engine. With this object in view I; provide, according to my invention, a mechanism for the compressor which includes a reversible drive and'means for reversing the drive if the direction of rotation of the reversible engine is changed.

For a better understanding of what I consider to be novel and my invention, attention is directedto the following description and the claims appended hereto in connection with the drawing which forms a part of my specification.

In the drawing I have shown, by way of example, partly diagrammatic and partly broken away, an arrangement for driving a compressor from a reversible engine in accordance with my invention.

Referring to the drawing, 1 represents a reversible engine, such as a combustion engine, having a shaft 2. 3 is a compressor including a casing 4 and impeller blades 5 secured to a rotary shaft 6. For driving the compressor from the reversible engine I provide, according to my invention, means including a reversible 7 drive '7. The latter includes an intermediate 59 shaft 8 driven from the reversible engine shaft 2,

in the present instance shown by means of pulleys 9, 10 and a belt 11. Provided on each end of shaft 8 is a half 12, 13 of a coupling, in the present instance shown as an ordinary friction 55 coupling. The other halves, 14 and 15 are provided on shafts 16 and 17 respectively. Shaft 16 is connected to the compressor shaft 6 by means of a gear 18 fastened toshaft 16 and meshing with a gear 19 provided on a shaft 20- from which compressor shaft 6 is driven by means of a belt drive 21. In a similar way shaft 1'? drives compressor shaft 6 by means of a belt drive 22. It will be seen that with shaft 17 rotating in a certain direction shaft 6 rotates in the same direction, and with shaft 16 rotating in the opposite direction as shaft 17 it causes rotation of shaft 6 inthe same directionas if driven from shaft 17-. The arrangement is such that with the reversible engine shaft 2 rotating in a certain direction, one of 7 the couplings 13, 15 and 12, 14 respectively is closed. whereas the other is opened. The closing and opening is performed by a motor,

in the present instance shown as a hydraulic motor comprising a cylinder 23 with a piston- 24 movable therein and having the opposite ends of its stem 25 pivotally connected to fulcrumed levers 26' and 27 respectively.

The upper end of each lever is provided with a fork 28 projecting into a groove of coupling 0 members 1 4 and 15 respectively. The halves 14 and 15 are free tomove or slide axially on shafts 16. and 1'? respectively but prevented from relative rotative movement on these shafts by keys 29 and 30 respectively. In the position shown in the drawing where the cylinder piston 24 is moved to the right, coupling 13, 15 is closed, whereas coupling 12, 14 is opened.

The hydraulic motor is controlled by means of a pilot valve 31 having valve heads 32 and ports 33 and 34 for connecting the pilot valve to opposite ends of the cylinder. 35 is an inlet port through which oil or like actuating fluid is supplied from any suitable source, not shown.

36 are discharge ports. In the position shown, actuating fluid is supplied through ports 35, 33 to the left-hand end of the hydraulic cylinder whereby the piston is forced towards the right, port 34 communicating with discharge port 36, thus permitting the draining of actuating fluid 190 from the right-hand end of the cylinder. The reversing of the reversible drive mechanism is accomplished by reversing the position of the pilot or controlling valve by means of a mechanism 3'7 in response to the reversing of the engine shaft 2. Mechanism 37 has been shown by way of example as comprising a shaft 38 driven from the reversible shaft 2 through a gearing 39. Shaft 38 has a threaded portion 40, 41 and 42 are two fixed supports having recesses no for holding springs 43 and 44 respectively. The springs surround the shaft and are maintained in concentric relation therewith by collars 45 and 46 respectively. Fastened to the pilot valve stem 47 is a holder 48 for supporting a pin 49 which projects into the grooves of thread 40.

With such an arrangement, rotation of shaft 38 in clockwise direction if observed from the left-hand end of the shaft causes pin 49 to move towards the left until it reaches the position shown in the drawing in which holder 48 causes compression of spring 43. The pin remains in this position until the direction of rotation is reversed. As soon as this occurs, spring 43 biasing the holder 48 towards the right, effects engagement between the pin and the thread, and the thread as soon as engaged with the pin moves the pilot valve towards the right until the pin disengages the thread and compresses spring 44.

The operation of the arrangement is as follows: Rotation of shaft 2 in the direction indicated by arrow, that is, seen from the left-hand end in counter-clockwise direction, causes rotation of shaft 8 in the same direction if seen from the left-hand end. At the same time shaft 2 drives shaft 38 in a clockwise direction and thus automatically causes the pilot valve stem to move to the left which in turn effects through the hydraulic motor closing of coupling 13, 15. The compressor then is driven through belt drive 22 in the same direction as shafts 2 and 8, that is, in counter-clockwise direction if seen from the left-hand side. Shaft 20, which is coupled with shafts 6 and 16 through belt drive 21 and gears 18, 19 respectively, rotates in the same direction and causes shaft 16 to run idle in opposite direction.

.If now the direction of rotation of the reversible shaft 2 is changed, it causes a change in direction of rotation of shaft 38 to the effect that the pilot valve moves to the right and thus effects the supply of actuating fluid to the right-hand end of the hydraulic cylinder 23 and the draining of fluid from the left-hand end thereof. Piston 24 thereby moves to the left and effects disengagement or opening of coupling 13, 15 and engagement or closing of coupling 12, 14. Shaft 8, which now rotates in opposite direction as before, is thus coupled through coupling 12, 14 with the oppositely rotating shaft 16 which in turn transmits torque to compressor shaft 6 Without causing a change in direction of rotation.

In many cases reversible engines, such as combustion engines, assume different speeds for forward and backward running. As rotary compressors have a maximum efficiency for a definite speed, I provide an arrangement which causes the compressor to run at the same speed for both forward and backward running of the reversible engine. This is achieved in the present instance by providing different ratios for the torque transmitting means. In the drawing I have shown a ratio for the torque transmitting belt drive 22 different from that of the torque transmitting means between shaft 16 and 6, that is, of belt drive 21 and gearing 18, 19. During the reversing operation the speed of the compressor decreases and thereafter increases. In order to facilitate the acceleration of the masses, I make in a preferred embodiment of my invention the compressor rotor at least partly of light metal.

With my invention I have accomplished a simple and reliable arrangement for driving a rotary compressor from a reversible shaft. Any standard compressor may be used in my arrangement at an eficiency which is the same as if driven by a separator motor. The reversing of the drive takes place automatically as soon as the reversible shaft changes its direction of rotation and thus does not demand the attention of the operator.

Having described the method of operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof, I desire to have it understood that the apparatus shown is only illustrative and that the invention may be carried out by other means.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. The combination with a reversible shaft and a driven shaft for rotation in one direction only, of a reversible drive for driving the driven shaft in the same direction of rotation for both directions of rotation of the reversible shaft, said drive comprising an intermediate shaft, two other shafts, torque transmitting means between each of the two other shafts and the driven shaft, a coupling between each of the two other shafts and the intermediate shaft, means for automatically closing one of the couplings in response to rotation of the reversible shaft, and means for automatically opening the closed coupling and closing the other coupling in response to a change in direction of rotation of the reversible shaft.

2. The combination with a reversible shaft and a driven shaft for rotation in one direction only, of means for driving the driven shaft from the reversible shaft, said means including a reversible drive for driving the driven shaft in the same direction of rotation for both directions of rotation of the reversible shaft, a motor for reversing the reversible drive, a control member for the motor and means for automatically moving the control member in response to a change in direction of rotation of the reversible shaft.

FRIEDRICH SASS. 

